The Clinical Radiation Therapy Research Center has four sections: Clinical Radiation Oncology, Nuclear Medicine, Radiologic Physics and the Cancer Research Unit. It has a number of overall objectives: one is to provide optimal treatment to all cancer patients, and another is to participate with the Radiation Therapy Oncology Group in various clinical trials to develop new concepts of treatment through basic and clinical research. The Cancer Research Unit, which is the basic research section, has four groups: Cancer Biology, Cancer Immunology, Experimental Oncotherapy and Viral Oncogenesis. Research of all four groups is closely integrated and is primarily directed towards improved cancer treatment through obtaining a better understanding of the biological factors involved in the response of normal and malignant cell populations to treatment modalities. The experimental systems developed over the year provide the opportunity for obtaining quantitative information at the biochemical, cellular, tissue and animal levels. These systems include the gastrointestinal epithelium, hematopoietic & immunological systems, several transplantable tumor cell lines, a viral leukemia, and the PDP assay for growth fraction measurements in experimental and human tumors. Cancer treatment regimens utilizing multi-fraction irradiation, chemotherapeutic agents, immune stimulation and combined modality therapy are being quantitatively evaluated. It is felt that an increased understanding of the cellular and tissue events occurring in both normal and malignant tissues, initially unperturbed and following treatment with currently available modalities, will provide a basis for planning cancer treatment regimens with a rational a priori input. BIBLIOGRAPHIC REFERENCES: Concannon, J.P. Carcinoma of the Cervix. University of Pennsylvania Oncology Course, December 1977. Concannon, J.P. Immunity and Lung Cancer, Indian Congress of Radiology, Chandiagarh, India, January 1977.